Seeing more sunlight is linked to a low risk of dementia, scientists say

It’s nearly winter and the days are growing darker, bringing negative impacts for our mental and physical health through December.

But getting more sunlight can fight these effects, including lowering the risk of dementia, a study of accelerometer data from 90,000 people in the U.K. shows.

Frequent exposure to even the light peeking through clouds on an overcast day was tied to a 16 percent reduced risk of the neurodegenerative condition, Chinese researchers said in June.

Whereas seeing “less than 0.7 hours per day of bright daytime light was a stronger predictor of dementia than six established dementia risk factors” including obesity, drinking alcohol and suffering a brain injury, Wiley, the publisher of the eight-year study’s journal General Psychiatry, noted in a release detailing the findings.

While the observational study does not prove that sunlight stops or prevents dementia, the researchers suggested possible reasons for the connection.

For one, exposure to daylight could fix interrupted sleep-wake cycles. Similar interruptions were tied to dementia in previous research.

Daylight helps the brain sync to a clock based on the sun and aids the body in producing the sleep hormone melatonin when it’s time for bed.

Disrupted sleep and living on a different sleep-wake cycle than others was previously shown to raise risk, leading to damaged blood vessels that increase people’s chance of developing dementia.

Exposure to sunlight was also tied to less shrinking in the brain – another symptom tied to dementia, the study noted. This is commonly known as “brain atrophy,” the Alzheimer’s Association says.

“However, these exploratory associations require verification in future studies,” the authors noted. “Moreover, daytime light exposure may favorably modulate the pathogenesis of dementia. Light therapy has been found to alleviate neuroinflammation, synaptic transmission irregularities and mitochondrial dysfunction.”

Study participants wore the accelerometers on their wrists over the course of a week.

The researchers also assessed medical records, hospital information and death registry data to determine which participants were later diagnosed with dementia.

“Over a median follow-up of 8.1 years, 741 participants developed dementia,” Wiley said.

Dementia is the most common neurodegenerative condition in the U.S., and the Alzheimer’s Association estimates 7.4 million patients are living with Alzheimer’s disease, the most common form of dementia. The majority of Alzheimer’s patients are over the age of 65.

There is no cure for dementia or Alzheimer’s, but there are treatments that can improve cases and steps healthy people can take to reduce risk.

Some are as simple as getting at least 20 minutes of exercise daily and eating a diet rich in whole foods, such as the fruit-, fish and vegetable-heavy Mediterranean diet.

Both can benefit the brain by improving heart health, which increases blood and oxygen flow, the Association says.